Method for reducing physisorption during atomic layer deposition

ABSTRACT

The present invention provides a method and apparatus for an atomic layer deposition process. The apparatus includes a chamber adapted to receive a first precursor gas, at least one surface interior to the chamber, and an acoustic wave driver coupled to the at least one surface and adapted to drive acoustic waves along the interior surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to semiconductor processing,and, more particularly, methods and apparatus for atomic layerdeposition processes.

[0003] 2. Description of the Related Art

[0004] Atomic layer deposition is a technique for applying thin filmsto, for example, a semiconductor substrate. Although atomic layerdeposition is a relatively new technology compared to, e.g. chemicalvapor deposition, experimentation has shown that atomic layer depositionhas an outstanding ability to form ultra-uniform thin deposition layersover complex topology. For example, atomic layer deposition processeshave been used to deposit a one-atom-thick copper layer on a dielectriclayer. For another example, a one-molecule-thick tantalum nitridebarrier layer may be deposited on a low dielectric constant (low-K)dielectric film. Semiconductor devices formed using atomic layerdeposition techniques may have length scales of 65-nanometers and below.

[0005] A typical atomic layer deposition process includes a sequence ofgas flows. In one embodiment, a reactant precursor gas is provided to areactor chamber in which a workpiece has been placed. For example,tri-methyl aluminum may be provided to the reactor chamber for about0.5-10 seconds. Atoms or molecules in the first precursor gas form asaturated monolayer on the workpiece via chemisorption of the firstprecursor gas. A second precursor gas, e.g. a reducing and/or oxidizinggas, is then provided to the reactor chamber. For example, H₂O, O₃, orNH₃ gases may be provided to the reactor chamber for 0.5-10 seconds. Theatoms or molecules in the second precursor gas are also chemisorbed toform a first atomic or molecular layer from the saturated monolayer. Theatomic layer deposition process may be repeated to form a layer of anydesired thickness.

[0006] The high reactivity of the two precursor gases may result in gasphase nucleation when the reactant precursor gas and the reducing and/oroxidizing precursor gas are both present in the reactor chamber.Particles formed by the gas phase nucleation may contaminate theworkpiece and/or the reactor chamber. To reduce the amount of gas phasenucleation and the resulting contamination, the reactant precursor gasis typically purged from the reactor chamber before the reducing and/oroxidizing precursor gas is introduced into the reactor chamber. Forexample, the first reactant gas may be purged by injecting an inert gassuch as argon into the reactor chamber. The reducing and/or oxidizingprecursor gas may also be purged before other gases are introduced.

[0007] The duration of the purge depends, at least in part, on thedegree and kinetics of the physisorption on interior surfaces of thereactor chamber. The precursor gases may be adsorbed onto surfaces inthe reactor chamber when they are introduced into the reactor chamber,and the adsorbed precursor gases may then be desorbed during the purge.The desorbed precursor gases may increase the concentration of precursorgases in the reactor chamber during the purge step and thereby increasethe time required to purge the chamber. For example, the reactor chambermay be purged for about 2-10 seconds, or until the concentration of thereactant gas falls to about 10¹⁰ atoms/cc. Consequently, the throughputof the atomic layer deposition process is limited, at least in part, bythe duration of the purge.

SUMMARY OF THE INVENTION

[0008] In one aspect of the instant invention, an apparatus is providedfor performing an atomic layer deposition process. The apparatusincludes a chamber adapted to receive a first precursor gas, at leastone surface interior to the chamber, and an acoustic wave driver coupledto the at least one surface and adapted to drive acoustic waves alongthe interior surface.

[0009] In one aspect of the present invention, a method is provided forperforming an atomic layer deposition process. The method includesproviding a surface acoustic wave to at least one surface in a chamber,providing a first precursor gas to the chamber concurrent with providingthe surface acoustic wave, and removing a portion of the first precursorgas from the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements, and in which:

[0011]FIG. 1 is a schematic illustration of one exemplary atomic layerdeposition apparatus, in accordance with one embodiment of the presentinvention;

[0012]FIG. 2 shows a piezoelectric liner that may be used in the atomiclayer deposition apparatus shown in FIG. 1; and

[0013]FIGS. 3A and 3B show exemplary embodiments of interdigitalelectrodes that may be used in the atomic layer deposition apparatusshown in FIG. 1.

[0014] While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0015] Illustrative embodiments of the invention are described below. Inthe interest of clarity, not all features of an actual implementationare described in this specification. It will of course be appreciatedthat in the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

[0016]FIG. 1 schematically illustrates an exemplary atomic layerdeposition apparatus 100, in accordance with one embodiment of thepresent invention. The atomic layer deposition apparatus 100 includes areactor chamber 105, a first dispensing valve 110, a purging valve 112,a second dispensing valve 115, an isolation valve 120, an exhaustforeline 125, an exhaust pump 130, and a dispensing foreline 135.Persons of ordinary skill in the art having benefit of the presentdisclosure will appreciate that only those elements of the exemplaryatomic layer deposition apparatus 100 helpful for the understanding ofthe present invention are described herein. Additional elements, such asvalves, lines, pumps, and the like may be included in the atomic layerdeposition apparatus 100 without departing from the scope of the presentinvention.

[0017] In the illustrated embodiment, the reactor chamber 105 includesan inlet 140 coupled to the first dispensing valve 110, the purgingvalve 112, and the second dispensing valve 115. However, in alternativeembodiments, the first dispensing valve 110, the purging valve 112, andthe second dispensing valve 115 may be coupled to separate inlets. Thereactor chamber 105 also includes an outlet 145 that is coupled to theisolation valve 120, which may be coupled to the exhaust pump 130 viathe exhaust foreline 125.

[0018] A wafer 150 may be positioned on a heater 155 in the reactorchamber 105. For example, the wafer 150 may be a semiconductor substrateupon which an atomic layer is to be deposited. In the illustratedembodiment, the reactor chamber 105 also includes a showerhead 160 thatis positioned substantially above the heater 155. The showerhead 160 iscoupled to the inlet 140 such that the showerhead 160 is capable ofreceiving gases from the first dispensing valve 110, the purging valve112, and the second dispensing valve 115.

[0019] During an atomic layer deposition process, a sequence of gasflows may be provided to the reactor chamber 105. In the illustratedembodiment, when the first dispensing valve 110 is open, a firstprecursor gas, indicated by the arrow 165, is selectively diverted sothat it may flow through the inlet 140 to the showerhead 160 and intothe reactor chamber 105. A first portion of the first precursor gas 165may be deposited on the wafer 150 by, for example, chemisorption of theatoms and/or molecules in the first precursor gas 165. A second portionof the first precursor gas 165 may be adsorbed onto various interiorsurfaces, e.g. a surface 185, of the reactor chamber 105 by, forexample, physisorption of the atoms and/or molecules in the firstprecursor gas 165.

[0020] When the first dispensing valve 110 is closed, the firstprecursor gas 165 may be selectively diverted so that it flows throughthe dispensing foreline 135 to the exhaust pump 130. However, inalternative embodiments, the first precursor gas 165 may be selectivelydiverted so that it flows through the dispensing foreline 135 to asecond exhaust pump (not shown) or the first precursor gas 165 may notbe selectively diverted when first dispensing valve 110 is closed.

[0021] The first precursor gas 165 may be purged from the reactorchamber 105. In one embodiment, the first precursor gas 165 is purged byintroducing an inert gas, indicated by the arrow 170, through thepurging valve 112. For example, argon gas may be introduced into thereactor chamber 105 by opening the purging valve 112. The firstprecursor gas 165 may also flow into the chamber outlet 145, through theisolation valve 120 and the exhaust foreline 125 to the exhaust pump130. In one embodiment, the first precursor gas 165 may flow out of thereactor chamber 105 at the same time as the inert gas 170 is introducedinto the reactor chamber 105. However, persons of ordinary skill in theart will appreciate that, in alternative embodiments, the firstprecursor gas 165 may begin flowing out of the reactor chamber 105before or after the inert gas 170 is introduced into the reactor chamber105. In addition, atoms and/or molecules that were adsorbed onto thereactor walls during the first precursor gas phase will begin to desorbduring the purge phase. Desorption of the first precursor gas atomsand/or molecules from the reactor walls will increase with as theduration of the purge phase increases.

[0022] When the second dispensing valve 115 is open, a second precursorgas, indicated by the arrow 175, is selectively diverted so that itflows through the inlet 140 to the showerhead 160 and into the reactorchamber 105. A first portion of the second precursor gas 175 may bedeposited on the wafer 150 by, for example, chemisorption of the atomsand/or molecules in the second precursor gas 175. The atoms and/ormolecules in the second precursor gas 175 may also interact with atomsand/or molecules of the first precursor gas 165 that may remain in thereactor chamber 105. For example, atoms and/or molecules of the firstprecursor gas 165 that had previously been adsorbed onto the interiorsurfaces of the reactor chamber 105, and that remained after the purgephase, may be desorbed into the reactor chamber 105. This interactionmay form particles (not shown) that may contaminate the wafer 150.

[0023] The reactor chamber 105 includes one or more acoustic wavedrivers 180 that are capable of driving acoustic waves along the surface185 interior to the reactor chamber 105. For example, as will bediscussed in detail below, a controller 190 may provide an AC signal tothe acoustic wave driver 180 to excite surface acoustic waves thattravel along the surface 185. The surface acoustic waves may reduceadsorption of the first precursor gas 165 onto the interior surface 185during the first precursor gas phase thus reducing the amount of timerequired for the purge phase to “clean” the reactor walls throughdesorption. The surface acoustic waves may also enhance desorption ofthe first precursor gas 165 from the interior surface 185 during thepurge phase. Consequently, the concentration of the first precursor gasmay be reduced more rapidly during the purge phase and the duration ofthe purge phase may be correspondingly reduced. Furthermore, thethroughput of the atomic layer deposition apparatus 105 may beincreased.

[0024] In a first illustrative embodiment, the surface 185 is aninterior surface 185 of the reactor chamber 105. For example, theinterior surface 185 may be an inner surface of a wall of the reactorchamber 105. In this embodiment, the one or more acoustic wave drivers180 may be deployed on the interior surface 185 of the reactor chamber105. For example, the one or more acoustic wave drivers 180 may bepiezoelectric transducers deployed on the interior surface 185. Althoughnot necessary for the practice of the present invention, additionalacoustic wave drivers 180 may be deployed in the exhaust foreline 125.

[0025] In a second illustrative embodiment, illustrated in FIG. 2, thesurface 185 may be a piezoelectric liner 200 that is deployed proximateat least a portion of the inner wall of the reactor chamber 105 shown inFIG. 1. For example, the piezoelectric liner 200 may be a quartzpiezoelectric liner 200 that is deployed adjacent the vertical portionof the inner wall of the reactor chamber 105. In the illustratedembodiment, the piezoelectric liner 200 is a cylindrical piezoelectricliner 200 having upper and lower openings 205, which may allow access tothe reactor chamber 105. However, the piezoelectric liner 200 may haveany desirable shape such that it may be deployed adjacent any portion ofthe inner wall of the reactor chamber 105.

[0026] More than one piezoelectric liner 200 may be deployed within thereactor chamber 105. In one alternative embodiment, the piezoelectricliner 200 may be deployed adjacent the vertical portion of the innerwall of the reactor chamber and a second piezoelectric liner 210 may bedeployed adjacent an upper horizontal portion of the inner wall of thereactor chamber 105. In the illustrated embodiment, the secondpiezoelectric liner 210 has an opening 215 to allow access to thereactor chamber 105. Although the second piezoelectric liner 210 shownin FIG. 2 is circular, the shape of the second piezoelectric liner 210is a matter of design choice and not material to the present invention.Furthermore, in various alternative embodiments, additionalpiezoelectric liners 200, 210 may be deployed in the reactor chamber105. For example, a third piezoelectric liner (not shown) may bedeployed adjacent a lower horizontal portion of the inner wall of thereactor chamber 105.

[0027] One or more acoustic wave drivers 220 are deployed on thepiezoelectric liners 200, 210. In the illustrated embodiment, theacoustic wave drivers 220 include at least one pair of interdigitalelectrodes 225, which are coupled to the controller 190. In operation,the controller 190 provides a first AC signal having a first polarity toa first one of each pair of interdigital electrodes 225 and a second ACsignal having a second polarity, opposite to the first polarity, to asecond one of each of the pair of interdigital electrodes 225. As iswell known to those of ordinary skill in the art, the resulting variablevoltage difference between the pair of interdigital electrodes 225excites surface acoustic waves that travel along the piezoelectricliners 200, 210.

[0028]FIGS. 3A and 3B show first and second exemplary embodiments of theinterdigital electrode pairs 300, 310, respectively. In the firstexemplary embodiment of the interdigital electrode pair 300 shown inFIG. 3A, each of the interdigital electrodes 300 includes a conductivebackbone 320 that is electrically coupled to a plurality of conductiveprongs 325. The first and second AC signals may be transmitted to theplurality of conductive prongs 325 via the conductive backbone 320. Thenumber, length, and spacing of prongs 325 is a matter of design choiceand should not be considered as a limitation to the present inventionexcept to the extent specifically set forth in an appended claim.

[0029] A spectrum of the surface acoustic waves produced by theinterdigital electrode pair 300 depends on the geometry of theconductive backbone 320 and the conductive prongs 325. In the embodimentillustrated in FIG. 3A, the conductive prongs 325 are all approximatelythe same length. Consequently, the interdigital electrode pair 300produces a broad-band spectrum of surface acoustic waves when providedwith the first and second AC signals. For example, the surface acousticwaves may be excited at approximately the same frequency as the firstand second AC signals.

[0030] In the second exemplary embodiment of the interdigital electrodepair 310 shown in FIG. 3B, the interdigital electrodes 300 each includea conductive backbone 330 that is electrically coupled to a plurality ofconductive prongs 335, as in the first exemplary embodiment. However, inthe second exemplary embodiment, the lengths of the conductive prongs335 are selected to provide a predetermined frequency response, i.e. theinterdigital electrodes 310 are apodized. For example, in FIG. 3B, thelengths of the conductive prongs 335 are selected to overlap in a regionindicated by the dashed lines 340, which approximately correspond to aprofile given by sin(x)/x, where the variable x indicates a displacementalong the direction corresponding to the axis 345.

[0031] The apodized interdigital electrode pair 310 acts as a band passfilter when provided with the first and second AC signals. In theillustrated embodiment, the spectrum of the surface acoustic waves thatmay be formed by the apodized interdigital electrode pair 310corresponds approximately to the Fourier transform of the profilesin(x)/x. Although the apodized interdigital electrode pair 310 shown inFIG. 3B implements a band pass filter corresponding to the profilesin(x)/x, this is a matter of design choice and should not be consideredas a limitation of the present invention except to the extentspecifically set forth in an appended claim. Alternative embodiments ofthe present invention may implement any desirable band pass using anydesirable profile.

[0032] The spectrum of the acoustic waves may be varied by changing thegeometry of the interdigital electrode pairs 300, 310, changing the ACsignal, or any combination of the two. In one embodiment, a spectrum offrequencies is selected based upon the composition of the firstprecursor gas. For example, a range of frequencies, e.g. the bandranging from about 100 Hz to about 200 kHz, may be selected based uponthe mass of the molecules in the first precursor gas. In one embodiment,a midpoint frequency within the selected range of frequencies may thenbe increased when the mass of the molecules in the first precursor gasis decreased and decreased when the mass of the molecules in the firstprecursor gas is increased. Alternatively, the range of frequencies maybe selected, e.g. increased or decreased, based upon the composition ofthe first precursor gas.

[0033] The particular embodiments disclosed above are illustrative only,as the invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Accordingly, the protection sought herein is as set forth inthe claims below.

1. An apparatus, comprising: a chamber adapted to receive a firstprecursor gas; at least one surface interior to the chamber; and anacoustic wave driver coupled to the at least one surface and adapted todrive acoustic waves along the interior surface.
 2. The apparatus ofclaim 1, wherein the acoustic wave driver is adapted to drive thesurface acoustic wave in a selected range of frequencies.
 3. Theapparatus of claim 2, wherein the range of frequencies is selected basedupon the composition of the first precursor gas.
 4. The apparatus ofclaim 3, wherein the range of frequencies is selected based upon a massof the molecules in the first precursor gas.
 5. The apparatus of claim4, wherein the range of frequencies has a midpoint frequency, andwherein the midpoint frequency is decreased when the mass of themolecules in the first precursor gas is increased.
 6. The apparatus ofclaim 4, wherein the range of frequencies has a midpoint frequency, andwherein the midpoint frequency is increased when the mass of themolecules in the first precursor gas is decreased.
 7. The apparatus ofclaim 2, wherein the selected range of frequencies is chosen from anoverall range of about 100 Hz to about 200 kHz.
 8. The apparatus ofclaim 1, wherein the acoustic wave driver comprises at least one pair ofelectrodes.
 9. The apparatus of claim 8, wherein the pair of electrodesis a pair of apodized electrodes.
 10. The apparatus of claim 1, whereinthe acoustic wave driver comprises at least one transducer.
 11. Theapparatus of claim 1, wherein the at least one surface comprises asurface of a piezoelectric liner deployed in the chamber.
 12. Theapparatus of claim 11, wherein the piezoelectric liner is a quartzliner.
 13. The apparatus of claim 11, wherein the at least one surfacecomprises a plurality of piezoelectric liners.
 14. The apparatus ofclaim 1, wherein the at least one surface comprises an interior surfaceof the chamber.
 15. The apparatus of claim 1, further comprising a pumpcoupled to the chamber and operable to evacuate the first precursor gasfrom the chamber.
 16. The apparatus of claim 1, wherein the chamber isadapted to receive a second precursor gas.
 17. A method, comprising:providing a surface acoustic wave to at least one surface in a chamber,the surface acoustic wave having a frequency range selected to reduceadsorption of a first precursor gas onto the at least one surface;providing the first precursor gas to the chamber concurrent withproviding the surface acoustic wave; and removing a portion of the firstprecursor gas from the chamber.
 18. The method of claim 17, whereinproviding the surface acoustic wave comprises providing a first andsecond AC signal to a first and second electrode, respectively, andwherein the first and second AC signals have opposite polarities. 19.The method of claim 17, wherein providing the surface acoustic wavecomprises: selecting the range of frequencies to reduce adsorption ofthe first precursor gas onto the at least one surface.
 20. The method ofclaim 19, wherein selecting the range of frequencies comprises selectingthe range of frequencies based upon the composition of the firstprecursor gas.
 21. The method of claim 20, selecting the range offrequencies comprises selecting the range of frequencies based upon amass of the molecules in the first precursor gas.
 22. The method ofclaim 21, wherein selecting the range of frequencies comprises selectinga midpoint frequency in the range of frequencies, and further comprisingdecreasing the selected midpoint frequency when the mass of themolecules in the first precursor gas is increased.
 23. The method ofclaim 21, wherein selecting the range of frequencies comprises selectinga midpoint frequency in the range of frequencies, and further comprisingincreasing the selected midpoint frequency when the mass of themolecules in the first precursor gas is decreased.
 24. The method ofclaim 19, wherein selecting the range of frequencies comprises selectingfrequencies ranging from about 100 Hz to about 200 kHz.
 25. The methodof claim 17, wherein providing the first precursor gas comprises openinga valve coupled to the chamber.
 26. The method of claim 25, whereinremoving the portion of the first precursor gas comprises removing theportion of the first precursor gas using a pump.
 27. The method of claim17, wherein removing the portion of the first precursor gas from thechamber comprises removing the portion of the first precursor gas fromthe chamber concurrent with providing the surface acoustic wave.
 28. Themethod of claim 17, further comprising providing a second precursor gasto the chamber after removing the portion of the first precursor gasfrom the chamber.
 29. An apparatus, comprising: means for providing asurface acoustic wave to at least one surface in a chamber; means forproviding a first precursor gas to the chamber; and means for removing aportion of the first precursor gas from the chamber.
 30. The apparatusof claim 29, wherein the means for providing the surface acoustic wavecomprises means for providing the surface acoustic wave having theselected range of frequencies.
 31. The apparatus of claim 29, whereinthe means for providing the first precursor gas comprises a valvecoupled to the chamber.
 32. The apparatus of claim 29, wherein the meansfor removing the portion of the first precursor gas comprises a pump.33. The apparatus of claim 29, wherein the means for removing theportion of the first precursor gas is a purge gas.
 34. The apparatus ofclaim 29, further comprising means for introducing a purge gas into thechamber to remove at least a portion of the first precursor gas.
 35. Theapparatus of claim 29, further comprising means for introducing a secondprecursor gas into the chamber after removing at least a portion of thefirst precursor gas.
 36. A processing chamber for performing an atomiclayer deposition process, comprising: a chamber having at lest one inletthrough which a first precursor gas and a purge gas may be introducedinto the chamber; and an acoustic wave driver coupled to a surfaceinterior to the chamber, the acoustic wave driver being operable togenerate a surface acoustic wave along the surface.
 37. The processingchamber of claim 36, wherein the acoustic wave driver is adapted todrive the surface acoustic wave in a selected range of frequencies. 38.The processing chamber of claim 37, wherein the range of frequencies isselected based upon the composition of the first precursor gas.
 39. Theprocessing chamber of claim 38, wherein the range of frequencies isselected based upon a mass of the molecules in the first precursor gas.40. The processing chamber of claim 39, wherein the range of frequencieshas a midpoint frequency, and wherein the midpoint frequency isdecreased when the mass of the molecules in the first precursor gas isincreased.
 41. The processing chamber of claim 39, wherein the range offrequencies has a midpoint frequency, and wherein the midpoint frequencyis increased when the mass of the molecules in the first precursor gasis decreased.
 42. The processing chamber of claim 37, wherein theselected range of frequencies is chosen from an overall range of about100 Hz to about 200 kHz.
 43. The processing chamber of claim 36, whereinthe acoustic wave driver comprises at least one pair of electrodes. 44.The processing chamber of claim 43, wherein the pair of electrodes is apair of apodized electrodes.
 45. The processing chamber of claim 36,wherein the acoustic wave driver comprises at least one transducer. 46.The processing chamber of claim 36, wherein the at least one surfacecomprises a surface of a piezoelectric liner deployed in the chamber.47. The processing chamber of claim 46, wherein the piezoelectric lineris a quartz liner.
 48. The processing chamber of claim 46, wherein theat least one surface comprises a plurality of piezoelectric liners. 49.The processing chamber of claim 36, wherein the at least one surfacecomprises an interior surface of the chamber.
 50. The processing chamberof claim 36, further comprising a pump coupled to the chamber andoperable to evacuate the first precursor gas from the chamber through anexhaust foreline.
 51. The processing chamber of claim 50, wherein atleast a portion of the at least one surface is within at least a portionof the exhaust foreline.
 52. The processing chamber of claim 36, whereina second precursor gas may be introduced into the chamber through the atleast one inlet.
 53. The processing chamber of claim 52, wherein the atleast one inlet comprises first, second, and third inlets through whichthe first precursor gas, the purge gas, and the second precursor gas,respectively, may be introduced into the chamber.
 54. The processingchamber of claim 36, wherein the at least one inlet comprises a firstinlet through which the first precursor gas may be introduced into thechamber and a second inlet through which the purge gas may be introducedinto the chamber.
 55. A method for performing an atomic layer depositionprocess, comprising: introducing a workpiece in a chamber; providing asurface acoustic wave to at least one interior surface in the chamberthe surface acoustic wave having a frequency range selected to reduceadsorption of a first precursor gas onto the at least one surface; andintroducing the first precursor gas into the chamber.
 56. The method ofclaim 55, further comprising removing at least a portion of the firstprecursor gas.
 57. The method of claim 56, wherein removing the portionof the first precursor gas comprises removing the portion of the firstprecursor gas using a pump.
 58. The method of claim 56, furthercomprising introducing a purge gas into the chamber to remove at least aportion of the first precursor gas.
 59. The method of claim 56, furthercomprising continuing to provide the surface acoustic wave to the atleast one interior surface in the chamber while removing at least aportion of the first precursor gas.
 60. The method of claim 56, furthercomprising introducing a second precursor gas into the chamber afterremoving at least a portion of the first precursor gas.
 61. The methodof claim 60, further comprising providing the surface acoustic wave tothe at least one interior surface in the chamber while introducing thesecond precursor gas into the chamber.
 62. The method of claim 60,further comprising: removing at least a portion of the second precursorgas from the chamber; and re-introducing the first precursor gas intothe chamber while providing the surface acoustic wave to the at leastone interior surface in the chamber.
 63. The method of claim 55, whereinproviding the surface acoustic wave comprises providing a first andsecond AC signal to a first and second electrode, respectively, andwherein the first and second AC signals have opposite polarities. 64.The method of claim 55, wherein providing the surface acoustic wavecomprises: selecting the range of frequencies to reduce adsorption ofthe first precursor gas onto the at least one surface.
 65. The method ofclaim 64, wherein selecting the range of frequencies comprises selectingthe range of frequencies based upon the composition of the firstprecursor gas.
 66. The method of claim 65, selecting the range offrequencies comprises selecting the range of frequencies based upon amass of the molecules in the first precursor gas.
 67. The method ofclaim 66, wherein selecting the range of frequencies comprises selectinga midpoint frequency in the range of frequencies, and further comprisingdecreasing the selected midpoint frequency when the mass of themolecules in the first precursor gas is increased.
 68. The method ofclaim 66, wherein selecting the range of frequencies comprises selectinga midpoint frequency in the range of frequencies, and further comprisingincreasing the selected midpoint frequency when the mass of themolecules in the first precursor gas is decreased.
 69. The method ofclaim 64, wherein selecting the range of frequencies comprises selectingfrequencies ranging from about 100 Hz to about 200 kHz.